The present invention is applicable to the fields of manufacturing and checking foldable boxes. A foldable box may, for example, be a cardboard packaging box. As a general rule, a foldable box in the folded state comprises a plurality of panels joined together by folds, and a plurality of flaps joined to the panels. Two neighboring flaps are separated by a slot extending between a central region and a peripheral face of the foldable box. The slot has a peripheral end opening on the peripheral face and delimiting a lateral interval between the two neighboring flaps.
In the prior art, an installation for manufacturing foldable boxes comprises a gluing device, a device for folding the panels of each foldable box, a stacking device for stacking the foldable boxes, and a conveying device for moving each foldable box between the gluing, folding and stacking devices.
EP0937573A1 discloses a checking device comprising an illumination system for illuminating each foldable box and a camera for forming images of each foldable box, one by one, in the course of movement by a roller conveyor means. The function of a checking device of this kind is, notably, to determine whether each foldable box does or does not conform to the established specifications.
However, the checking device of EP0937573A1 is placed at a location where the foldable box has not yet undergone all the specified processes. Thus, after the camera has formed an image of the slots separating the flaps, each foldable box undergoes other processes which may modify the state of the foldable box. It may happen, therefore, that the checking device of EP0937573A1 assesses a foldable box as non-conforming even though this foldable box could have become conforming after squaring. Therefore, using the checking device of EP0937573A1 results in a relatively large number of rejected foldable boxes.